The present invention relates to a power saving method of an image forming apparatus, such as a laser beam printer, and more particularly, to a power saving method of an image forming apparatus which automatically performs a warm-up operation when the image forming apparatus has been in a power saving mode for a predetermined time period, thereby reducing the waiting time for a printing operation.
Recently, an energy star computer program sponsored by the U.S. Environmental Protection Agency (EPA) allows manufacturers of energy efficient office equipment complying with specified contractual terms and conditions to use a designed energy star logo indicating the energy efficiency of their product. The energy star computer program is a cooperative effort between the U.S. Environmental Protection Agency and computer device manufactures to promote the production and sale of energy efficient office equipment. The program is particularly aimed at reducing air pollution resulting from the generation of power necessary to operate currently available office equipment. Accordingly, the program encourages the production of office equipment having power-saving features. Such equipment consumes less power, and thus helps reduce the production of air pollution. In an image forming apparatus, however, after power is turned on, the amount of time a user must wait before printing can be performed often exceeds the amount of time necessary for performing the actual printing. Prolonged stand-by times cause unnecessary power consumption attributable to operation of a heat lamp or a ventilating fan. In order to reduce unnecessary power consumption, after a given time period passes while in a stand-by state, a fan or fusing unit of the engine controller, for example, turns off to initiate a power saving mode. According to Environmental Protection Agency standards, this given time period is typically fifteen minutes. In order to perform a printing operation during the power saving mode, the fan and/or fusing unit of the engine controller must be adequately warmed up.
One prior art device equipped with a power saving mode is disclosed in U.S. Pat. No. 4,745,436 entitled Copying Machine issued to Matsuura on 17 May 1988. In an effort to enable rapid printing with minimal waiting, Matsuura '436 provides that a power saving mode can be cancelled automatically in response to any one of the operations relating to the start of the printing operation. Such operations include: placing a manuscript on the platen of the device, closing the device cover or pressing a copy start button. While such conventional art has merit in its own right, we believe that it can be improved.
Another conventional apparatus for reducing power consumption in peripheral devices of a computer is disclosed in U.S. Pat. No. 4,980,836 entitled Apparatus For Reducing Computer System Power Comsumption issued to Carter et al. on 25 December 1990. In Carter et al. '836, peripheral equipment, such as a printer, enters a low-power (stand-by) mode when it has not been accessed for a preset amount of time. A manual switch is provided in order to return the device to a normal power level, when so desired by the user. That is, this type of conventional art remains in the low-power mode until activated by the user. Accordingly, we believe that the conventional art can be improved to reduce the waiting time experienced by the user when the device is returning to its normal power level.